Effects of glycyrrhizic acid and steroid treatment on corticotropin releasing factor and beta-endorphin containing neurons of the hypothalamus of the rat

Corticotrophin releasing factor (CRF) and beta-endorphin (beta EP) containing neurons are shown to be present in the hypothalamus and both neurons are found at the paraventricular nucleus (PVN). Steroid hormones have been found to alter the plasma level of these neurotransmitters. Glycyrrhizic acid (GCA) is the active component of liquorice. GCA inhibits the enzyme 11 beta-hydroxysteroid dehydrogenase (11HSD) which is needed for the inactivation of the steroid pathway, so therefore would cause changes to these neurons. The aim of this study was to investigate the effects of GCA as well as deoxycorticosterone (DOC) and dexamethasone (DM) on the modulation of CRF and beta EP containing neuron at the PVN of the hypothalamus. Rats were given either DM, DOC or GCA and adrenalectomized (ADX) and given either DM or DOC. At the end of treatment rats were transfused transcardially before sacrifice and the brain were dissected for immunohistochemical analysis. We found that immunostaining of the CRF containing neurons demonstrate a reduction in the number of positive neurons in DM treated rats. DOC and GCA treated rats showed the same result as in DM rats but the reduction is less. ADX, DM, DOC and GCA treated rats did not show any changes in the number of beta EP containing neurons but naloxone increased the number of beta EP containing neurons markedly. In conclusion, GCA and DOC have similar effects on CRF and beta EP containing neurons at the PVN.     

Antimicrobial susceptibilities and plasmid contents of Neisseria gonorrhoeae isolates from commercial sex workers in Dhaka, Bangladesh: emergence of high-level resistance to ciprofloxacin

Commercial sex workers (CSWs) serve as the most important reservoir of sexually transmitted diseases (STD), including gonorrhea. Periodic monitoring of the antimicrobial susceptibility profile of Neisseria gonorrhoeae in a high-risk population provides essential clues regarding the rapidly changing pattern of antimicrobial susceptibilities. A study concerning the prevalence of gonococcal infection among CSWs was conducted in Bangladesh. The isolates were examined with regards to their antimicrobial susceptibility to, and the MICs of, penicillin, tetracycline, ciprofloxacin, cefuroxime, ceftriaxone, and spectinomycin by disk diffusion and agar dilution methods. The total plasmid profile of the isolates was also analyzed. Of the 224 CSWs, 94 (42%) were culture positive for N. gonorrhoeae. There was a good correlation between the results of the disk diffusion and agar dilution methods. Some 66% of the isolates were resistant to penicillin, and 34% were moderately susceptible to penicillin. Among the resistant isolates, 23.4% were penicillinase-producing N. gonorrhoeae (PPNG). 60.6% of the isolates were resistant and 38.3% were moderately susceptible to tetracycline, 17.5% were tetracycline-resistant N. gonorrhoeae, 11.7% were resistant and 26.6% had reduced susceptibility to ciprofloxacin, 2.1% were resistant and 11.7% had reduced susceptibility to cefuroxime, and 1% were resistant to ceftriaxone. All PPNG isolates contained a 3.2-MDa African type of plasmid, and a 24.2-MDa conjugative plasmid was present in 34.1% of the isolates. Since quinolones such as ciprofloxacin are recommended as the first line of therapy for gonorrhea, the emergence of significant resistance to ciprofloxacin will limit the usefulness of this drug for treatment of gonorrhea in Bangladesh.     

Abnormalities of cholesterol metabolism in autism spectrum disorders.

Although Smith-Lemli-Opitz Syndrome (SLOS), a genetic condition of impaired cholesterol biosynthesis, is associated with autism [Tierney et al., 2001; Am J Med Genet 98:191-200.], the incidence of SLOS and other sterol disorders among individuals with autism spectrum disorders (ASD) is unknown. This study investigated (1) the incidence of biochemically diagnosed SLOS in blood samples from a cohort of subjects with ASD from families in which more than one individual had ASD and (2) the type and incidence of other sterol disorders in the same group. Using gas chromatography/mass spectrometry, cholesterol, and its precursor sterols were quantified in 100 samples from subjects with ASD obtained from the Autism Genetic Resource Exchange (AGRE) specimen repository. Although no sample had sterol levels consistent with SLOS, 19 samples had total cholesterol levels lower than 100 mg/dl, which is below the 5th centile for children over age 2 years. These findings suggest that, in addition to SLOS, there may be other disorders of sterol metabolism or homeostasis associated with ASD.     

Adaptive Wiener Filtering for Improved Acquisition of Distortion Product Otoacoustic Emissions

An innovative acoustic noise canceling method using adaptive Wiener filtering (AWF) was developed for improved acquisition of distortion product otoacoustic emissions (DPOAEs). The system used one microphone placed in the test ear for the primary signal. Noise reference signals were obtained from three different sources: (a) pre-stimulus response from the test ear microphone, (b) post-stimulus response from a microphone placed near the head of the subject and (c) post-stimulus response obtained from a microphone placed in the subjects nontest ear. In order to improve spectral estimation, block averaging of a different number of single sweep responses was used. DPOAE data were obtained from 11 ears of healthy newborns in a well-baby nursery of a hospital under typical noise conditions. Simultaneously obtained recordings from all three microphones were digitized, stored and processed off-line to evaluate the effects of AWF with respect to DPOAE detection and signal-to-noise ratio (SNR) improvement. Results show that compared to standard DPOAE processing, AWF improved signal detection and improved SNR. © 1998 Biomedical Engineering Society. PAC98: 4364Jb, 4360-c, 8790+y     

Molecular and genetic characterizations of five pathogenic and two non-pathogenic monoclonal antiphospholipid antibodies

Antiphospholipid syndrome (APS) is an autoimmune disease that is characterized by thrombosis, recurrent fetal loss and thrombocytopenia. Antiphospholipid antibodies, detected by enzyme-linked immunoabsorbent assays (aCL) and/or in vitro blood clotting assays (LAC) are strongly associated with APS. Both the molecular structures used by pathogenic antiphospholipid antibodies and the genetic mechanisms leading to their production are unknown. We describe here the variable region genes of seven IgG antiphospholipid antibodies derived from two APS patients. Of these, five are pathogenic as defined in a mouse model of thrombosis and two are not. Analyses of the expressed variable region genes show no preferential V gene usage. However, similar to anti-DNA antibodies, pathogenic antiphospholipid antibodies contain an increased number of arginine residues in the third complimentarity-determining region (CDR3) of their H chains. The increased accumulation of arginine residues in the V(H) CDR3 may act to enhance antigen binding, promote disease and point to the importance of the H chain in the pathogenic potential of certain antiphospholipid antibodies.     

The (α2→8)-Linked Polysialic Acid Capsule and Lipooligosaccharide Structure Both Contribute to the Ability of Serogroup B Neisseria meningitidis To Resist the Bactericidal Activity of Normal Human Serum

The molecular basis for the resistance of serogroup B Neisseria meningitidis to the bactericidal activity of normal human sera (NHS) was examined with a NHS-resistant, invasive serogroup B meningococcal isolate and genetically and structurally defined capsule-, lipooligosaccharide (LOS)-, and sialylation-altered mutants of the wild-type strain. Expression of the (α2→8)-linked polysialic acid serogroup B capsule was essential for meningococcal resistance to NHS. The very NHS-sensitive phenotype of acapsular mutants (99.9 to 100% killed in 10, 25, and 50% NHS) was not rescued by complete LOS sialylation or changes in LOS structure. However, expression of the capsule was necessary but not sufficient for a fully NHS-resistant phenotype. In an encapsulated background, loss of LOS sialylation by interrupting the α2,3 sialyltransferase gene, lst, increased sensitivity to 50% NHS. In contrast, replacement of the lacto-N-neotetraose α-chain (Galβ1-4GlcNAcβ1-3Galβ1-4Glc) with glucose extensions (Glc_N) in a galE mutant resulted in a strain resistant to killing by 50% NHS at all time points. Encapsulated meningococci expressing a Hep₂(GlcNAc)→KDO₂→lipid A LOS without an α-chain demonstrated enhanced sensitivity to 50% NHS (98% killed at 30 min) mediated through the antibody-dependent classical complement pathway. Encapsulated LOS mutants expressing truncated Hep₂→KDO₂→lipid A and KDO₂→lipid A structures were also sensitive to 50% NHS (98 to 100% killed at 30 min) but, unlike the wild-type strain and mutants with larger oligosaccharide structures, they were killed by hypogammaglobulinemic sera. These data indicate that encapsulation is essential but that the LOS structure contributes to the ability of serogroup B N. meningitidis to resist the bactericidal activity of NHS.Serogroup B Neisseria meningitidis (the meningococcus) is an obligate human pathogen and remains a leading cause of fulminant septicemia and meningitis. In addition to sporadic outbreaks, large epidemics of serogroup B meningococcal disease continue to occur in many parts of the world, including South America, the United States Pacific Northwest, Western Europe, and New Zealand (4, 22). After penetrating upper respiratory tract mucosal surfaces, N. meningitidis must survive and multiply in the bloodstream to cause sepsis, meningitis, and other manifestations of invasive meningococcal disease. A major mechanism inhibiting or preventing the multiplication of meningococci in the blood is the complement-mediated bactericidal activity of human sera (17, 39). The importance of this activity in the prevention of systemic meningococcal disease is reinforced by host factors that alter bactericidal activity and increase the risk for development of invasive disease. These factors include the absence of bactericidal antibodies against meningococci (17, 18, 45), deficiencies in the complement cascade (13), and the presence of blocking immunoglobulin A antibodies that inhibit the bactericidal activity of human sera (19). The bactericidal activity of human sera against meningococci is also used as a surrogate marker for assessing meningococcal vaccine efficacy.Meningococci have evolved mechanisms that protect them from the bactericidal activity of human sera. Invasive serogroup B meningococcal strains recovered from blood and cerebrospinal fluid often resist being killed by human sera (48). The molecular basis for resistance has been attributed to the expression by this organism of an (α2→8)-linked polysialic acid capsule and a short-chained lipooligosaccharide (LOS) with terminal sialic acid residues (23, 34, 35). Meningococci isolated from the bloodstream in invasive disease, in contrast to nasopharyngeal isolates, are heavily encapsulated (9) and express the L3,7,9 LOS immunotypes (28). These immunotypes have a lacto-N-neotetraose originating from HepI of the inner core, which may be terminally sialylated (34, 62). However, the experimental data defining the precise contributions of the capsule, LOS sialylation, and LOS structure to the ability of serogroup B meningococci to resist the bactericidal activity of human sera is conflicting (11, 15, 20, 21, 27, 37, 63–65).LOS epitopes are immunogenic in infants and children and induce protective bactericidal antibodies in convalescent sera (10, 12). These bactericidal LOS antibodies appear to be directed at conserved low-molecular-weight LOS epitopes (10, 12). LOS is also a component of new serogroup B outer membrane vesicle (OMV) vaccines and is proposed as a basis for other new meningococcal vaccines (1–3, 50). Although changes in the structure of LOS are known to influence the amount and epitopes of bactericidal and other functional antibodies elicited by OMV vaccines (2), the precise LOS structure(s) to include in these and other LOS-containing meningococcal vaccines is uncertain.To help understand the basis for meningococcal survival following mucosal invasion and to facilitate development of meningococcal vaccines which may contain LOS, we created a series of genetically and structurally defined capsule-, sialylation-, and LOS-altered mutants of the serogroup B meningococcal strain NMB. We used these mutants to study the contributions of the capsule, LOS sialylation, and changes in LOS structure to meningococcal resistance to the bactericidal activity of normal human sera (NHS).     

Synthesis and physical properties of telechelic monodispersed diols 4. Monoaddition of 10-undecenol to novel dithiols

The synthesis of novel telechelic monodispersed diols produced from the radical monoaddition of an excess of 10-undecenol with novel α, ω-dithiols, initiated by peroxides, is presented. The telechelic dithiols employed were prepared from nonconjugated dienes and a commercially available dithiol, or by esterification of adipic acid with 2-mercaptoethanol. From these dithiols, the diols were selectively obtained in high yields. Such α, ω-dihydroxylated compounds were characterized by both ¹H and ¹³C NMR spectroscopy. The diol which exhibits the ester functions shows excellent solubility in common organic solvents contrarily to the other ones. The physical properties (T_g, T_m and decomposition temperatures) of these diols were compared and it is noted that the thermostability of these monodispersed telechelic diols is much better than those of the polydispersed commercially available ones such as poly(ethylene glycol)s or poly(tetramethylene glycol)s.